I do find myself having to make sure all the time that I don't click on the root ownership option when I want the open as root option, so I say that having them next to each other with such similar menu descriptions is not a good idea and inviting such accidents.

+1. it may be unlikely since little reporting on users doing this, but if they do it is a very bad result.

IMHO, the Ownership to Root & Ownership to user right click actions in Thunar have a high possibility of unintended consequences relative to their utility. We have the delete key in Thunar mapped to Send to Trash where they can be recovered if necessary instead of to delete for the same reason.
If we leave them there, I would separate them from the much more useful Open root Thunar here & Edit as Root instead of having them stuck between them where it is easier to select them by mistake.

What about this compromise - good for "normal" user and also for experts:
We keep as a maintenance option Root-Thunar within the right-click menu
and move Change-Ownership options to the right click menu of the running Root-Thunar.
Advantage:
Normal user cannot accidentally shoot themselves in the food.
Experts can have Root-Thunar as they have now to their liking.
including the option to change ownership within maintenance mode.

There's either an unexpected syntax change, or it's outputting to stderr.

The OP did run the inxi with a system in a bad shap,
had all set-uid/setgrouid permissions revoked and some more ( all under /usr/bin with group ownership to root).
So I assume, this triggerd something.
EDIT: clarified "some more"

Re root user for a file manager, there are many reasons you want that. It's particularly helpful if you work with reasonably large sets of root owned files, for example Apache configurations etc. I personally view the lack of a root file manager as a real production pain. I don't use these often, but when I need it, not having it really costs me time.

This is kind of in the realm of: Don't confuse the fact you don't need something with the fact that that something has many uses that you simply don't need yourself, but which others do.

Re root user for a file manager, there are many reasons you want that. It's particularly helpful if you work with reasonably large sets of root owned files, for example Apache configurations etc. I personally view the lack of a root file manager as a real production pain. I don't use these often, but when I need it, not having it really costs me time.

This is kind of in the realm of: Don't confuse the fact you don't need something with the fact that that something has many uses that you simply don't need yourself, but which others do.

Good points Don't forget we have switch-to-other user, where you can have a full root session, switching with one key-stroke between normal user session and a root session.